merge with develop, includes MP4Reader and Utils cleanup.

v2.1 - Improved Datatype Tolerance

fix for mp4 with only one GPMF payload

version 2.0 - security and memory fixes

version 1.5.1 includes minor changes preparing for v2

Update README.md

Add new camera metadata descriptions

Version bump to reflect previous small change to GPMF_Init

V1.2.2 improved handling of corrupted sources

Improved handling for corrupted MP4 headers.

Version 1.2.1